Treatment of paraffin hydrocarbons



Jan 25, 1944,` A. R. GoLDsBY E-rAL 2,339,349

TREATMENT OF PARAFFIN HYDROGARBONS Filed June so, 1939 ARTHUR R.GoLnsaYEUGENE ESENssl.

INVENTORS s Y E N n A m E H T Patented Jan. 2 5, 1944 UNITED STATESPATENT 1f orifice .TREATMENT oF rm maooAaBoNs. I y

o! Delaware Application June so, 1939, sei-loi No. 282,114' .l ,f i.

1o claims (o1. '26osaam l 'Ihis invention relates to the treatment orreforming 4oi naphthas and has to do particularly with the isomerizationof straight run or virgin naphthas to improve the antiknock value andvolatility.

Straight run naphthas from parainic or mixed base crudes contain largeamounts of parafn hydrocarbons which consist in substantial amount ofstraight chain hydrocarbons having a relatively low antiknock value. Itis an object of the present invention to convert a substantial amount ofsuch straight chain paraiin hydrocarbons into branch chain orisoparaflin hydrocarbons of high antiknock value.

It has been proposed heretofore to isomerize certain normally gaseoushydrocarbons and lower boiling normally liquid hydrocarbons, such asnormal butane and normal pentane, to corresponding isoparamns b ycontacting the normal parailns in the liquid or vapor phase attemperatures' of zero to 200 C., with certain anhydrous metallichalides, such as chlorides, bromides, etc. of aluminum, zinc, iron,zirconium, tin, barium, columbium, tantalum and boron, and small amountsof hydrogen halides, such as hy#- drogen` chloride, as promoters. It hasalso been proposed to subject gasoline of boiling range of about 130 to190 F. to isomerization 1n the presence of aluminum, chloride andhydrochloric" acid I and accompwying deterioration of the catalyst whichni'f-lnally occur with the higher boiling normal paraiins, may besubstantially inhibited or by carrying out the isomerizationoperation'fin the presence of a large proportion of a low boilingisoparaiiln, such as isobutane and isopentane. Moreover, the formationof high boiling. material above the gasoline boiling range is avoided..The reactions involved are not fully understood. It isthought that theisoparailin may inhibit the cracking and the resultant formation ofunsaturated hydrocarbon fragments or A a continuous operation.

olens; or the isoparamn may react with the olens as formed to producesaturated alkylation products; lor a combination of the above tworeactions may occur.

The catalysts which are useful includel any of v the activelsomerization catalysts, such as metallic halides, preferably used inthe presence of small amountsof promoters, such as hydrogen halides.While any ofthe anhydrous metallic halides which will function asalkylationcatalysts are contemplated, for practical purposes aluminumhalides, such as aluminum chloride, and alu, minum bromide arepreferred. Likewise any of the hydrogen halide promoters, such as HC1.HBr, H1 and HF, may be used, but it is preferable to use hydrogenchloride. The metallic halide catalyst may be in solid, granular or lumpform, or in the case of AlBrs attemperatures above 208 F. in liquidform, or supported on a solid absorbent such as synthetic and naturalclays, pumice, brick, coke, activated alumina, and activated carbon. Thehydrogen halide promoter may be added as such or may be generated insitu from the metallic halide by adding the rewhich reacts with themetallic halide.v

The process may be carried out in a batch or continuous type ofoperation, and preferably 'in The process is'preferably conducted as acyclic operation in which the isoparatiinis recycled together with anyPortion or all of the hydrogen halide promoter.

The amount of catalyst and promoter will vary. depending on the type ofoperation used. In a batch operation, it is contemplated that thecatalyst may be about l to '40% or more by weight `based on the weightof tne hydrocarbon charge. The promoter may vary between about 0.1 and:1% or more, and preferably about 1%. In continuous operations, whereinthe promoter is 'recycled, the range of the amounts of the catalyst andpromoter will be much broader. For example,.tne amount of catalyst mayrange from 1 to 100% or more. while the promoter may vary 'from about0.05 to 50% or more.

The invention is not restricted to any par-l ticular temperature andpressure. since the process may be operated successfully attemperatures` and pressures selected from quite wide ranges..

Thus, temperatures may range f'om about room temperature to about'300 F.The pressures may under atmospheric or subatmospheric pressures.

'I'he proportion of isoparaflin is influenced by the operatingconditions and the nature of the charge. Larger amounts of isoparaiiinare advantageous when using higher temperatures and higher percentagesof promoter and catalyst. Also when using the higher molecular weightchargestocks itis desirable to use higher ratios of isoparaln.

It is contemplated that the isoparaillns may vary from about 25% byvolume of the hydrocarbon charge up to 1000% or more, and preferably aratio of isobutane to hydrocarbon charge from about 1:1 to 5:1.

For purposes of illustration and without in any way limiting theinvention, examples are given below of the treatment of straight rungasoline in the presence of aluminum chloride and hydrogen chloride,with and without the addition of isobutane. Example I is a batchoperation, without the addition of isobutane. Example 1I is an operationsimilar to Example I except isobutane is added according to theinvention. Example III is a continuous operation using added isobutanein accordance with the invention. In Examples II and III the gasolinewas converted into a product of improved volatility and antiknock valuewith substantially no loss from catalyst deterioration, whereas inExample I the gasoline was impaired in volatility and there was asubstantial loss in the form of a liquid complex of hydrocarbon anddeteriorated catalyst.

Example I A straight run gasoline from Mid-Continent crude oil was mixedwith 20% of granular aluminum chloride, and 2.5% of HCl by weight. Themixture was agitated for 3 hours at about 198 to 204 F.

The percentage of the gasoline charge recovered as gasoline and o-gaswas 86.8%. The amount of hydrocarbons in the gasoline charge combinedwith the catalyst to form a dark reddish colored liquid-aluminumchloride-hydrocarbon complex containing all of tHe catalyst was 11.1%.The remaining products comprised HC1 and'gases lost during the reaction.

'Ihe tests on the original gasoline and gasoline product afterstabilization, are as follows:

Before i Alter treatment 10% A' sl" mu treatment with ich with Alon 13oI. B. P 2i ies 67. 120 iso 10a ist 19s 20 i60 211 30 184 222 40 204 23250 225 240 60 241 250 70. 25o 200 sofr 280 274 r m 99. 0 Percent rec 96.0

1 o Percent res 0. 9

Percent loSS 3. 1

C. F. R. M. knock rating 53.9 No. tetraethyl lenti... 67.5

65.0 1 0c. tetraethyl lead..-- 79.4

73.0 2 cc. tetraethyl lead 83.5

Example II Another sample of the same gasoline as used in Example I wasagitated with 20% by weight of granular aluminum chloride, 5.1% byweight of HCl and about 386% by weight of isobutane based on thegasoline charged, in a pressure autoclave for three hours at about 190to 200 F.

The products consisted of a gasoline and isobutane layer and a catalystlayer which differed from Example I in that the catalyst layer was not aliquid but a granular solid much the same as the original aluminumchloride'.

The untreated and stabilized treated gasolines tested as follows:

untreated 10% A. s. r. M. distillation i Treated 5 0 9 36 C. F. R. M.octane number. 63 3 The volatility of the upper portion of the dis-vtillation range is improved, over Example I above, and the end point iswithin the gasoline range.

Example' 1H A straight run Mid-Continent naphtha, similar to that in thepreceding examples, and isobutane in the ratio of about four partsisobutane by volume to one of naphtha, and about 0.5% byweight 'of HC1based onthe mixture, is continuously fed to a tower containing aluminumchloride wherein the mixture is contacted with the catalyst at about to210"v F.` After separating any complex and catalyst, the reactionproducts are subjected to debutanization to separate the gases,containing isobutane and HC1, which are recycled. About 95% to 99% ofthe naphtha with an octane increase of about 10 points is recovered.

The invention is applicable to the treatment of various fractions ofnormally liquid paraiiln hydrocarbons, such as pentane, hexane, heptaneor octane, or mixtures of two or more thereof as well as virgin naphthasof various boiling ranges.

The invention will be further. understood from the accompanying drawingwhich shows a diagrammatic sketch of one form of apparatus for carryingout continuously the process of the invention.

Referring to the drawing, the charge stock is introduced through theline I by the pump 2 into catalyst chamber or tower 4 containing thecatalyst 5. Any liquid complex or partially spent catalyst in reactor 5may be withdrawn from this reactor through line E. The aluminum chloridecontained in the complex may be recovered by destructive distillation ofthe complex. The reaction products are transferred from the upperportion of the catalyst chamber through the line l 2,389,849 Theseparator. or the reaction products entering the separator, may becooled to facilitate precipitation of the catalyst.` The hydrocarbonsare passed from the separator through the line II ,tol a debutanizer orfractionator I2 wherein the hydrogen chloride and normally gaseoushydrocarbons, comprising chiefly isobutane, are separate'd and removedoverhead through thel vapor line I5 and condenser I6. If isopentane isused 1 instead of or with the isobutane, it may also be removed all orin part with the overhead from the fractionator I2. `The overheadproducts may berecycled all or in part through the line I8, pump I9 andline 20 to the catalyst chamber. In case the products removed overheadfrom the debutanizer I2 contain constituents which are undesirable forrecycling, such as propane, it may be desirable to remove such materialsor to discard a fraction in order to prevent them from building up inthe system. For this purpose, any portion of the products may be passedthrough the line 2| by the pump 22 to a fractionator 24.

In the fractionator a separation is made between` isobutane and/orisopentane and lighter gases which are released from the upper portionof the fractionator through the line 25. The isobutane fractionv iswithdrawn from the lower portion of the fractionator through the line 26and may be passed all or in part through the line 38 by the pump 31 forrecycling. If desired, hydrogen chloride may be recovered from the lightgases withdrawn from fractionator 24 through line 25, and recycled toreactor 5.

The debutanized hydrocarbons are withdrawn from the bottom ofthe'debutanizer through the.

line 28, pump 29 and line 30 to a fractionator 3|. In the fractionator3| the products are fractionally distilled to separate the gasolinefraction from bottoms which are withdrawn from the lower portion of thefractionator through the line 32. The gasoline vapors are removedoverhead from the fractionator through the line 33 and condenser 34 toan accumulator 35.

Obviously many modifications and variations of the invention, ashereinbefore set forth, may be made without departing fromthe spirit andscope thereof, and therefore only such limitations should be imposed asare indicated in the appended claims.

We claim:

1. A process for improving the antiknock value of naphtha rich in normalparailins which comprises subjecting the naphtha to contact with a.`

metallic halide isomerization catalyst -normally .tending todeteriorate, and form hydrocarbon complex, and eecting the contacttreatment at an isomerizing temperature not in excess of about 300 F.and in the presence of an added isoparaffin ofthe class of isobutaneandisopentane in amount by weight substantially in excess of the weightof the naphtha feed and such that naphtha feed hydrocarbons areisomerized to products the reaction in the proportion of from aboutfourA to ten volumes lof isoparaiiins to one volume of naphtha.

5. A process for the isomerizatlon of naphtha hydrocarbonswhichcomprises continuously passing a stream of naphtha feed hydrocarbonthrough a reaction zone containing an isomerizatlon catalyst maintainedunder conditions such that isomerizationconstitutes the principalreaction and such that the reaction is normally ac` companied byformation of a small amount of material boiling above the gasolineboiling range, continuously introducing to said zone a stream of lowboiling isoparafn hydrocarbon in an amount suiiicient to maintaintherein low boiling isoparaiiin in an amount-substantially greater byboilingisoparaflln at a temperature not in excess of about 300 F. withsubstantial reduction in cracking and catalyst deterioration over thatobtaining when the reaction'is eected in the absence o'f added lowboiling isoparaflin, and continuously removing from the reaction zone areacted hydrocarbon mixture containing isomerized naphtha hydrocarbons.

6.- The process according to claim 5 in which the catalystcomprisesmetallic halide activated with hydrogen halide.

7. The process according to claim 5 in which the low boiling isoparaiiinhydrocarbon maintained in the reaction zone consists essentially ofisobutane.

8. The process according to claim 5 in which the low boiling isopa-ainmaintained in the reaction zone amounts to at least about 400% by volumeof the naphtha feed hydrocarbon undergoing treatment.

9. A process for the isomerization'of naphtha hydrocarbons whichcomprises continuously passing a stream of naphtha. feed hydrocarbonthrough a reaction zone containing an isomerization catalyst maintainedunder conditions such that isomerization constitutes the principalreaction and such that the" reaction is normally accompanied byformation of a small amount of material boiling above the gasolineboiling range. continuously introducing to said zone a stream of lowboiling isoparaiiin hydrocarbon in an amount suflicient to maintaintherein low boiling isoparail'in in an amount substantially greater byvolume than the naphtha feed undergoing treatment therein and suicientat least to substantially reduce the formation of said high boilingmaterial, effecting substantial isomerization` of naphtha feed in thepresence of the added low boiling isoparain with substantial reductionin cracking and catalyst deterioration over that obtaining when thereaction is eiected in the ab of improved antiknock value withoutsubstantial catalyst deterioration and with relatively little conversionto hydrocarbons boiling below and above the boiling range of the naphthafeed.

2. The method according to claim 1 in which the catalyst comprisesaluminum chloride and hydrogen chloride.

3. The method according to claim 1 in which the catalyst comprisesaluminum chloride and hydrogen chloride and the contact treatment iseffected at a temperature of about 190 to 210 F.

4. The method according to claim `1 in which the isopar'aiiln and thenaphtha are charged to sence of added low boiling isoparain. and con`said reaction zone. subjecting it therein to contact with the catalystin the presence o! a low boiling isoparamn. added to the reaction,effecting substantial lsomerization of naphtha feed hydrocar-bons withsubstantial reduction in cracking and catalyst deterioration over thatobtained when the reaction is effected inthe absence of added lowboiling isoparaln, continuously discharging from the reaction zone 'astream of isomer-ization naphtha hydrocarbons and added low boilingisoparamn, separating from the discharged stream an isoparamn fractionlower boil- .ing than. said lsomerized naphtha' hydrocarbons andrecycling said separated lsoparamn fraction to the reaction zone in anamount'sumcient to provide therein low boiling isoparamn in an amountsubstantially greater by volume than the naphtha feed undergoingltreatment therein and ysulllcient at least to substantially reducethefor-

